Validation of pulse oximetry for monitoring of hypoxaemic episodes in the late postoperative period.

We monitored 12 patients undergoing major abdominal surgery using a pulse oximeter (Nellcor N-200) and a transcutaneous oxygen tension monitor (TINA, Radiometer A/S) on the second or third night after operation. Of the shortest hypoxaemic episodes measured with the pulse oximeter (< or = 30 s duration), 78% also occurred in the transcutaneous oxygen tension measurement. Episodes of longer duration (> or = 1 min duration on the pulse oximeter) were, in 95% of cases, reflected in the transcutaneous oxygen tension measurement also. Thus postoperative episodic desaturations lasting > or = 1 min are at least 95% likely to be a real phenomenon.